Apparatus for testing porous materials



O 1935- R. SCHOPPER 2,021,948

APPARATUS FOR TESTING POROUS MATERIALS Filed June 22. 1931 ny..a.

Patented Nov. 1935 PATENT omen mans-ms roa ras'rmc roaous RudolfSehopper, Lelpflg,

Application June 22,

' In Germany 19:1, Serial No. 546.034 May as, 1931 11 Claims. (01. 73-51) My invention'relates to means for testing the permeability, forinstance, the permeability to air, of porous materials, such as ordinarypaper, coarse paper for bags and the like, filtering paper 5 and othermaterials. It has particular reference to apparatus of the type in whichair is sucked through the material under test with constant suction bymeans of a Mariotte flask.

A Mariotte flask, as is known,jis a vessel of glass or other suitablematerial which has a discharge opening at the bottom and a suction orair-inlet pipe which extends into the vessel from .above. The flask isfilled with water or other liquid to a levelabove the lower end of thepipe 16 and the head under which the liquid flows fromthedischargeopeningisequaltothevertical distance of this opening fromthe lower end of the suction or air-inlet pipe, irrespective of thelevel of the liquid in the flask, so that the head 20 under which theliquid flows from the discharge opening is constant for any level ofliquid above the lower end of the suction or air-inlet pipe.

. In the apparatus referred to, the Mariotte flask.

is movable. It is an object of my invention to 24 so design an apparatusof which a Mariotte flask forms part, that its operation is performedunder more favorable and convenient conditions, and is simplifiedthereby. 1

To this end, I provide a' Mariotte flask which 3 is stationary, incombination with a discharge pipe whose outlet opening is adapted to bedisplaced vertically with respect to the flask, and a measuring tank forthe reception of the liquid flowing from the outlet opening. Preferably,the 35, measuring tank is connected to the discharge pipe and moves withthe pipe.

The piece of material to be tested is secured to the upper end of thesuction pipe so that the air which is drawn into the flask through thesuction pipe to make up for the liquid discharged from the flask,permeates the test piece. If the upper end of the suction pipe is notobstructed by a test piece, the volume of make-up air which is drawn inthrough the suction pipe per unit of 4. time, is equal to the volume ofliquid which is discharged from the discharge pipe during the same unit,for a given head from the lower end of the suction pipe to theoutlet'opening of the discharge pipe. If a test piece is inserted, the

5 flow of the make-up air is obstructed more or less, in conformity withthe degree of permeability of' the material under test. For a test pieceof a given permeability and for a given head, the flow of the liquidfrom the flask generates agiven'reduction of pressurein the suction pipebelow the test piece. The relation of the reduction of pressure belowthe test piece to the head of liquid from the lower end of the suctionpipe to the outlet end of the discharge pipe, or to the volume of liquiddischarged per unit of time which 6.

obviously is a function of the head, is a measure of the permeability ofthe material. If one of the two factors, the reduction of pressure orthe head, is maintained constant, the variation of the other factor fora test piece of material oth- -10- pressure (which is the constant) hasbecome equal to the reduction under which the first test was performed,and the volume of liquid which flows from the discharge pipe under thishead per 0-- unit of time say, per minute, is measured. The volume, ascompared with the volume for the first test, is a measure for thevariation of the head which variation, in turn, is determined by thepermeability of the second test piece as compared with thepermeability'of the flrst piece. In this manner, the permeability of anymaterial may be determined as related to the permeability of a materialof known permeability. y

In the drawing afllxed to this specification and forming part thereofseveral forms of. an apparatus. embodying my invention are illustrateddiagrammatically by way of example. 7

In the drawing Fig. l is a partly sectional elevation of an apparatus inwhich the measuring tank is raised and lowered by means of arack-and-pinionmechanism,

Fig. 2 is a diagram of an apparatus in which the measuring tankand abalance weight are attached to opposite ends of a flexible member, sothat the tank is readily moved to any desired position, and

Fig. 3 is a diagram of an apparatus in which the measuring tank israised and lowered by a medium under pressure acting on a piston.

Referring now to the drawing, and first to Fig.

l, 2 is a frame which may be of cast iron, and I is a Mariotte flask onthe frame. 3 is the suction pipe of the Mariotte flask, 4 is a casing towhich the upper end of the suction pipe I is connected and 5 is the testpiecewhich is extended across the open top of the casing 4 and held bysuitable means, such asthe ring and thumb screws illustrated. 6 is apressure gauge connectedtothecasingl,'listheclosureoftheMariotteflask.lis aflllingfunnelwlthacock I, andllisanairvent,bothontheclosure'l.

The discharge pipe extends from the bottom of the flask i to the outletend of an overflow pipe ll. I2 is a nipple at the bottom of the flask,with a cock H. A flexible tube It connects the cock II' to thelower endoi the overflow pipe l4. i5 is a bracket on which the overflow pipe I4and a measuring tank it are supported, the upper curved end of theoverflow pipe opening above\ the tank I! which receives the liquiddischarged from the flask l.

The bracket II is mounted upon a rack which is fltted to slide in asuitable block 32, i8 is a pinion mounted in suitable bearings of theblock 32 and meshing with the rack i1, and I! is a crank on the shaft ofthe pinion. It will be understood that by rotating the crank I! the racki1 is raised and lowered, and the head from -the lower end oi thesuction pipe 3 to the opening of the overflow pipe I4 is varied. In theexample illustrated, the head is In in the upper position of themeasuring tank shown in full lines, and h: in the lower position shownin dotted lines. The head is a function of the permeability of the testpiece 5 and is varied by raising and lowering the measuring tank It soas to maintain a constant suction in the casing 4 which is indicated bythe pressure gauge S an may be 4 in. of water.

As explained in the introduction, the head of liquid from the lower endof the suction pipe 3 to the outlet of the discharge opening at theupperend of the overflow pipe ll, determinesthe volume of liquid which isdischarged from the flask I per unit of time. The suction in the casing4 is the constant, and the head It is the variable. For a material ofminimum permeability, the head is hi. For a denser material, theresistance to the flow of atmospheric air into the casing 4 is increasedand a greater head is required for drawing in so much air that theconstant suction in the casing 4 is re-established. The overflow pipe i4and the measuring tank ii are lowered until the gauge i again indicatesthe constant suction in the tank 4. The head to which the overflow pipell must be lowered for re-establishing the constant suction, is afunction of the permeability of the material under test but is notmeasured. What is measured is the volume discharged per unit of time,say, one minute, which volume obviously is a function of the variablehead.

Referring nowto Fig. 2, the Mariotte flask l and its accessories havebeen omitted in this and in the next flgure for the sake of convenience.a is 'an upright, 2| is a sheave at the upper end of the upright, is aflexible member, such as a cable or chain which is supported on thesheave 2i and secured to the bracket ii at one end and 22 is a balanceweight attached to its other end. 23 is a slide or clip on the bracketl5 which is guided on a bar 24. The slide serves not only for guidingbut also for handling the bracket i5 and is equipped with a set screw 34for holding it on the bar 24 at any desired level. Referring now to Fig.3, 25 is the rod oi a piston 26 to the upper end of which rod thebracket IS, with the measuring tank It, is secured. 21 is a cylinder inwhich the piston 26 is mounted to reciprocate, is a source of supply offluid under pressure, which may be in liquid or gaseous condition, ii isa three-way valve, and 28, 29 are pipes extending respectively to theupper and lower ends of the cylinder for distributing the fluid from thethree-way valve 3|.

By arranging the Mariotte flask I, with its suction pipe 3 and thecasing I for the test 5, in a flxed position the reading of the pressuregauge 6 is much facilitated as the gauge 6 is invariably in the sameposition, preferably at the level or the operator's eyes. Anotheradvantage of the flxed flask is that its capacity may be large since theflxed frame 2 may be made as strong 'as required, so that a great numberof tests may be performed in series without the flask requiringrefilling.

In series tests it is not necessary to return the overflow pipe I! toits zero. position after every test, but it is sufllcient to eflect aslight regulation of its position so as to reestablish the normalpressure, say 4 in. water, in the casing l.

I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described for obviousmodifications will occur to a person skilled in the art.

I claim:-

1. An apparatus for testing the permeability of porous materialscomprising a stationary Mariotte 25 flask, a discharge pipe connected tothe liquid space of said flask, means for displacing the outlet openingof said pipe vertically with respect to said flask, and a measuring tankguided for vertical reciprocation for receiving the liquid flow- 30 ingfrom said pipe.

2. An apparatus for testing the permeability of porous materialscomprising a stationary Mariotte flask, with a suction pipe, a casingfor supporting the test piece connected to said suction pipe, adischarge pipe connected to the liquid space of said flask, means fordisplacing the outlet opening of said pipe vertically withrespect to thelower end of said suction pipe, and a measuririg tank for receiving theliquid flowing from said 0 P De.

3. An apparatus for testing the permeability of porous materialscomprising a stationary Mariotte flask, with a suction pipe, a casingfor supporting the test piece connected to said suction 4 pipe, abracket adapted to be displaced vertically with respect to the lower endof said suction pipe, a discharge pipe which is connected to the liquidspace of said flask at one end and whose other or outlet end is mountedon said bracket,

and a measuring tank also mounted on said bracket for receiving theliquid flowing from said pipe.

4. An apparatus for testing the permeability of porous materialscomprising a stationary Mariotte flask, with a suction pipe, a casingfor supporting the test piece connected to said suction pipe, a bracketadapted to be displaced vertically with respect to the lower end of saidsuction pipe, means for guiding said bracket in a straight verticalline, a discharge pipe which is connected to .9 the liquid space of saidflask at one end and whose other or outlet end is mounted on saidbracket, and a measuring tank also mounted on said bracket for receivingthe liquid flowing from said p pe.

5. An apparatus for testing the permeability of porous materialscomprising a stationary Mariotte flask, with a suction pipe, a casingfor supporting the test piece connected'to said suction pipe,'a bracketadapted to be displaced vertically with respect to the lower end of saidsuction pipe, a rack and pinion mechanism for raising and lowering saidbracket, a discharge pipe which is connected to the liquid space of saidflask at one end and whose other or outlet end is mounted on N aoaneeaon said bracketior receiving the liquid flowing from said piper.

6. An apparatus tortesting thespermeability,

of porous materials comprising a stationary Mariotte flask, with a.suction pipe, a casing for. supe.

porting the twt piece connected to said suction pipe, a bracketadapted-to be displaced .verticalq,

1y with respect to the'lower end. ofsaid suction pipe, means for flxing'said bracket in a given position, a discharge pipe which is connected tothe liquid space of said flask at one'end and whose other or outlet endis mounted'on said bracket, and a measuring tank also mounted on saidbracket for receiving the liquid flowing from said pipe.-

'7. An apparatus for testing the permeability of. porous materialscomprising a stationary Mari-' otte flask, with a suction pipe, acasingfor supporting the. test piece connected to said suction pipe, a bracketadapted to be displaced vertically with respect to the lower end of saidsuction pipe, a fluid-controlled piston for raising and lowering saidbracket, a discharge pipe which'is connected to theliquid space of saidflask at one end and whose other or outlet end is mounted on saidbracket, and a measuring tank also mounted on said bracket for receivingthe liquid flowing from said pipe.

8. An apparatus for testing the permeability of porous materialscomprising a Mariotte flask, with a suction pipe, a casing forsupporting the test piece connected to said suction pipe, means forholding said flask in a flxed position, a measuring tank adapted to beraised and lowered, a

pipe line extending from the liquid space of said flask to and tank, .aflexiblemember operatively connected to said-measuring-tank atone end. asheave supporting said member,- =and a balance weight at theother endotsaid member. 1

. 9., Anrave -em {9 t e --i etm fliw of porous materialsco prising a- Matt fla t tniece connected to said'suction pip means 9 hcldins said flasi 'efliiims iqn. 3 urin tank adapted'to beraised arjidlowered; a 10 pipeline extending from theii'qiiid space'ot said flask to said tank. andmeans hicluding a set screw for fixing-said tank in-afgiveh' mama;

10.--'.An "apparatus for testing the "permeability of porous materialscomprising a'Mariotte flask, with a'suction pipe, a'c'ashig 'forsupporting the test piece connected to said suetio'n -pipe','--meansforholding said flask ina flxed'positiom-a bracket adapted to be raisedand-'lowered;- .a measuring tank arranged on'said bracket and a pipeline extending from the liquid space of said flask to said tank, a flxedbar, and a clip on said bracket mounted to slide on said bar,.andadapted to be held in any given position thereon.

11. An apparatus for testing the permeability of porous materialscomprising a Mariotte flask, with a suction pipe, a casing forsupporting the test piece connected to said suction pipe, means forholding'said flask in a fixed position, a measuring tank adapted to beraised and lowered, and a pipe iine'including a curved overflow pipeextending from the liquid space of said flask to said tank. v

RUDOLI' SCHOPPER.

